While the invention is not particularly limited to medical devices, it is indicated at the onset that a wide use of open-cell tantalum structures have been employed for bone implants and cells as well as tissue receptors. The use of materials such as sold under the trademark HEDROCEL by Implex Corporation, the assignee herein, utilizes a metallic porous cellular structure which is a biomaterial containing tantalum. Such structures are extremely useful and for example, are described in detail in U.S. Pat. No. 5,282,861 issued on Feb. 1, 1994, and entitled "OPEN CELL TANTALUM STRUCTURES FOR CANCELLOUS BONE IMPLANTS AND CELL AND TISSUE RECEPTORS" to Richard B. Kaplan and assigned to Ultramet of Pomona, Calif.
In that patent there is described the need for a cancellous bone substitute and/or cell and tissue receptive material. The "Background of the Invention" of the '861 patent gives detail on the prior art as well as various structures that are employed. In the patent there is described a reticulated open cell carbon foam which is infiltrated with tantalum by the chemical vapor deposition (CVD) process.
It is noted that niobium which has similar chemical and mechanical properties to tantalum may also be used as well as appropriate alloys of tantalum and niobium. A carbon foam is infiltrated by chemical vapor deposition (CVD). The resulted lightweight strong porous structure basically resembles the microstructure of bone and acts as a matrix for the incorporation of bone or for the reception of cells and tissues. The pores of this particular material are connected to one another to form continuous uniform channels of no dead ends. This network of interconnected pores provides optimal permeability in a high surface area to encourage cell and tissue ingrowth. It is desirable to utilize a material such as that and bond that material to another metallic layer or to another substrate.